JP2004120918A - Frequency stabilizer - Google Patents

Abstract

A frequency stabilizing apparatus that calculates a required load control amount and quickly limits a load when a frequency drop occurs due to a system fault reduces the number of high-speed facilities on a transmission line to reduce costs.
A control terminal (3a, 3b) for limiting control of loads (4a to 4f) connected to a plurality of buses (1a, 1b) in an electric power system is provided for each bus. 1a and 1b are collected and the frequency is monitored, and the system reference information with small fluctuation due to the system accident is acquired from the central control device 10 at intervals of, for example, 10 minutes. When the system accident occurs, the collected information is collected. Each of the control terminals 3a and 3b calculates a load control amount, and performs load limitation on the loads 4a to 4f connected to the buses 1a and 1b according to the load control amount.
[Selection diagram] Fig. 1

Description

【００１１】
次に、第２の情報収集手段によりｓ３にて収集し保持している系統の慣性定数Ｍ、系統容量Ｐ_Ｌ０およびｓ４にて算出した値を用い、系統事故発生に起因した発電機脱落後の出力演算値Ｐ_Ｇ０’を以下の数式（３）に従って算出する。なお、発電機事故前出力Ｐ_Ｇ０は、系統容量Ｐ_Ｌ０とロス分のみの違いであり、系統容量Ｐ_Ｌ０から算出しても良いし、便宜上同じ値を用いても良い（ｓ５）。
【００１２】
【数２】

【００１３】
次に、系統全体における必要な負荷制御量Ｐ_ＬＣを以下の数式（４）に従って算出する（ｓ６）。
【００１４】
【数３】

【００１５】
次に、当該制御端末３ａ、３ｂの分担率Ｋ_ｉにより、当該制御端末３ａ、３ｂでの必要な負荷制御量Ｐ_ＬＣｉを以下の数式（５）に従って算出する（ｓ７）。
【００１６】
【数４】

【００１７】
次に、当該制御端末３ａ、３ｂでの負荷制御量Ｐ_ＬＣｉに応じて、制限、遮断する負荷４ａ〜４ｆを選択し、選択された負荷４ａ〜４ｆを制限、遮断する遮断器８ａ〜８ｆに負荷制限の指令信号を出力ケーブル９を介して出力する（ｓ８）。
以上の動作（ｓ１〜ｓ８）を、各制御端末３ａ、３ｂで行い、各制御端末３ａ、３ｂからの指令信号を受信した遮断器８ａ〜８ｆは該指令に応じて負荷４ａ〜４ｆの制限、遮断を行う。
【００１８】
この実施の形態では、各制御端末３ａ、３ｂを母線毎１ａ、１ｂに設け、各制御端末３ａ、３ｂが、第１の情報収集手段により当該母線１ａ、１ｂに係る計測情報を収集して、系統の周波数Ｆを計測して該周波数Ｆを監視すると共に、第２の情報収集手段により中央制御装置１０から所定の時間間隔で、系統の慣性定数Ｍ、系統容量Ｐ_Ｌ０などの系統基準情報を収集して、それぞれ当該制御端末３ａ、３ｂでの負荷制御量を演算して遮断器８ａ〜８ｆに負荷制限の指令信号を出力することで、周波数安定化を行う。
ここで、第２の情報収集手段により中央制御装置１０から受信する系統の慣性定数Ｍ、系統容量Ｐ_Ｌ０および負荷遮断の分担率Ｋ_ｉなどの系統基準情報は、上述したような周波数低下を伴う系統事故により急激に変化するものではなく、殆ど変動しない、あるいは連続的に緩やかに変動するものである。このため、事故時に、例えば２００ｍｓｅｃ程度で負荷制限の制御を行うことが必要であるが、各制御端末３ａ、３ｂにおける第２の情報収集手段による中央制御装置１０からの受信間隔は１０分に１回程度の長い時間間隔でよく、高価な高速伝送路を必要としない。
【００１９】
また、系統事故により変化の大きな情報は、第１の情報収集手段により母線１ａ、１ｂに係る計測情報として収集しており、各制御端末３ａ、３ｂは母線毎に設けているため、自端にてケーブル７を介し高速に情報収集が可能になる。さらに、各制御端末３ａ、３ｂにてそれぞれ負荷制御量を演算して遮断器８ａ〜８ｆに負荷制限の指令信号を伝達するにも、短い出力ケーブル９で高速に伝達可能になる。
このように、伝送路の高速設備が削減でき、コスト低減が図れる。
【００２０】
実施の形態２．
上記実施の形態１において、ｓ５にて発電機脱落後の出力演算値Ｐ_Ｇ０’を上記数式（３）により算出したが、以下の数式（６）に従って算出しても良い。
【００２１】
【数５】

【００２２】
このように、負荷４ａ〜４ｆの電圧静特性係数αを所定値に設定し、第１の情報収集手段によりｓ１にて収集された母線電圧を用いて、上記数式（３）による算出式に、系統事故による母線１ａ、１ｂの電圧変動を考慮する補正値（Ｖ_Ｌ／Ｖ_Ｌ０）^αを乗算することにより、母線電圧変動による算出誤差を補正することができ、発電機脱落後の出力演算値および必要な負荷制御量の演算精度が向上し、信頼性の高い周波数安定化制御が行える。
【００２３】
実施の形態３．
上記実施の形態１において、各制御端末３ａ、３ｂではｓ３にて中央制御装置１０から、所定の時間間隔で系統基準情報である慣性定数Ｍおよび系統容量Ｐ_Ｌ０を受信したが、既に受信された情報を用いて次回の受信時までの間に、慣性定数Ｍおよび系統容量Ｐ_Ｌ０を推定演算しても良い。この推定演算について以下に説明する。
系統の慣性定数Ｍ、系統容量Ｐ_Ｌ０は、それぞれ各制御端末３ａ、３ｂの制御対象の負荷量Ｐ_Ｌｉとほぼ比例関係にある。このため、第１の情報収集手段により当該制御端末３ａ、３ｂの負荷量Ｐ_Ｌｉを取得し、この負荷量Ｐ_Ｌｉの変化に応じて慣性定数Ｍ、系統容量Ｐ_Ｌ０を以下の数式（７）、数式（８）に従って算出する。なお、基準とする時点ｔ_０は、通常前回の受信時点を指すが、それ以前の受信時点であってもよい。
【００２４】
【数６】

【００２５】
このような推定演算は、例えば、系統の慣性定数Ｍおよび系統容量Ｐ_Ｌ０を受信する時間間隔が、例えば１０分であれば、その間に、例えば受信後５分経過時に自動的に行って演算値を保持するようにしても良いし、ｓ２にて系統事故が認識された時点で演算して、ｓ５での発電機脱落後の出力演算値Ｐ_Ｇ０’の算出に用いても良い。
これにより、第２の情報収集手段による受信間隔が大きくても、その間の情報を推定演算することにより上記系統基準情報の信頼性が高まり、発電機脱落後の出力演算値および必要な負荷制御量の演算精度が向上し、信頼性の高い周波数安定化制御が行える。また、第２の情報収集手段による中央制御装置１０からの受信が何らかの故障により途絶えた場合にも、既に受信された情報を用いて推定演算された系統基準情報が得られるため、周波数安定化制御が継続して行える。
【００２６】
なお、ｓ５での演算は、上記実施の形態２を適用して母線電圧変動による算出誤差を補正しても良い。
また、系統の慣性定数Ｍおよび系統容量Ｐ_Ｌ０の推定演算方法は、上述したものに限るものではなく、例えば、前回と前々回との受信情報から変動を推定して、例えば比例計算により最新の情報を推定させても良い。
【００２７】
【発明の効果】
以上のようにこの発明に係る周波数安定化装置は、電力系統内の複数の母線に接続される負荷の制限制御を行う制御端末を各母線毎に配し、この各制御端末に、第１、第２の情報収集手段と、収集された情報を用いて負荷制御量を演算する手段と、この負荷制御量に応じて母線に接続された負荷に対する負荷制限を行う手段とを設ける。また、各制御端末は、第１の情報収集手段にて、母線に係る計測情報を収集して上記電力系統の周波数を監視し、第２の情報収集手段にて、第１の情報収集手段による収集情報に比して系統事故による変動が小さい系統基準情報を、制御対象電力系統全体の監視および制御を行う中央制御装置から取得する。このため、中央制御装置と各制御端末とを結ぶ高速伝送路を必要とせず、高価な高速伝送設備を削減でき、周波数安定化装置の装置構成を安価にでき、周波数安定化制御のコスト低減が図れる。
【図面の簡単な説明】
【図１】この発明の実施の形態１による周波数安定化装置の概略構成を示す図である。
【図２】この発明の実施の形態１による周波数安定化装置における各制御端末の動作を示すフローチャートである。
【図３】この発明の実施の形態１による周波数安定化装置の算出された周波数偏差のイメージ図である。
【符号の説明】
１ａ，１ｂ　母線、３ａ，３ｂ　制御端末、４ａ〜４ｆ　負荷、
１０　中央制御装置。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a frequency stabilizing device that controls a frequency drop that occurs in a power system in the event of system disconnection or generator dropout to an appropriate frequency.
[0002]
[Prior art]
In a conventional frequency controller for stabilizing the frequency of an electric power system, a tidal current value and a system frequency flowing through a transmission line of the electric power system are measured, and a central calculation is performed together with the capacity of the generator ascertained at a central power supply command center. The central processing unit calculates the control amount necessary for controlling the frequency of the power system to an appropriate value. That is, when the frequency of the system is abnormally lowered, the central processing unit needs to increase the frequency. Therefore, the central processing unit obtains the required load control amount, and cuts off the load in order to cut off the load amount corresponding to the control amount. A trip signal is output to the selected control terminal and the breaker is tripped (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-10-108368 (page 2, FIG. 7)
[0004]
[Problems to be solved by the invention]
Since the frequency stabilization of the conventional power system has been performed as described above, the required load control amount is calculated by the central processing unit that controls the entire power system to be controlled, and the load is limited immediately when an accident occurs. To do so, information at the time of an accident was transmitted and collected at high speed, and a trip signal for limiting the load was transmitted to a control terminal connected to the load at high speed. For this reason, high-speed transmission equipment such as a high-speed transmission line connecting the central processing unit and each control terminal is required, and there has been a problem that cost reduction is difficult.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is an object of the present invention to reduce the number of high-speed transmission paths used for signal transmission and to configure an inexpensive power system frequency stabilizing device. Aim.
[0006]
[Means for Solving the Problems]
The frequency stabilizing apparatus according to the present invention includes a control terminal for performing load limiting control connected to a plurality of buses in the power system for each bus. Each of the control terminals is provided with first and second information collecting means, means for calculating a load control amount using the collected information, and load limiting for a load connected to the bus in accordance with the load control amount. And means for performing the same. In addition, each control terminal collects measurement information related to the bus with the first information collecting means, monitors the frequency of the power system, and uses the first information collecting means with the second information collecting means. System reference information that has less fluctuation due to a system accident than the collected information is acquired from a central control device that monitors and controls the entire power system to be controlled.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a frequency stabilizing device according to Embodiment 1 of the present invention.
As shown in FIG. 1, a plurality of buses 1a to 1d in the power system to be controlled are linked between the buses by transmission lines 2a to 2d. The buses 1a to 1d are provided with control terminals 3a and 3b, respectively, for controlling the loads 4a to 4f or the generators 5a to 5c connected to the buses 1a to 1d. Here, in order to explain the control of the loads 4a to 4f, the control terminals 3a and 3b are illustrated only for the buses 1a and 1b to which the loads 4a to 4f are connected, and the illustration and description of the other components are omitted. In each of the control terminals 3a and 3b, the bus information detected by the sensors (transformers) 5a and 5b and the bus voltages detected by the sensors (current transformers) 6a to 6f as the measurement information related to the buses 1a and 1b. The transmission line current is collected via the input cable 7, and a load limiting command signal is output via the output cable 9 to circuit breakers 8 a to 8 f which limit and cut off the loads 4 a to 4 f. In addition, the monitoring and control of the entire power system are performed by the central control device 10 in accordance with a command from the central power supply command station 11, and each of the control terminals 3a and 3b transmits system reference information described later from the central control device 10. Obtained via the transmission path 12.
[0008]
Next, the operation of frequency stabilization will be described below with reference to the flowchart of FIG. The operation of frequency stabilization in the frequency stabilization device according to the present invention is performed centering on the control terminals 3a, 3b provided in each bus 1a, 1b. Here, the operation of each control terminal 3a, 3b is performed. Is illustrated in FIG. 2 and will be described in detail.
At normal times, in each of the control terminals 3a and 3b, the bus information detected by the sensors (transformers) 5a and 5b and the sensor (current The transmission line currents detected by the devices 6a to 6f are collected via the input cable 7, the system frequency F is measured, and the frequency F is monitored (s1). That is, by measuring the variation amount of the frequency F with respect to the reference frequency F ₀ which is set in advance to determine whether an accident should be controlled to the power system occurs on the basis of the variation amount (s2).
Further, at predetermined time intervals (for example, every 10 minutes) from the central control device 10 by the second information collecting means, the system inertia constant M, the system capacity P _L0 (load amount), and the control terminal The load sharing ratios K _i (integer constants) in 3a and 3b are received, and the previous received information is updated and held (s3).
[0009]
For example, when a system fault occurs in the transmission line 2c and the amount of generated power is insufficient, or when a fault involving a frequency drop such as a power loss occurs, a system fault is recognized in s2.
Next, based on the information collected in s1 by the first information collecting means, the frequency deviation ΔF and its change dΔF / dt are calculated, for example, according to the following equations (1) and (2). Note that (T ₁ , ΔF ₁ ) and (T ₂ , ΔF ₂ ) are two data of the frequency deviation at the time of or immediately after the recognition of the system fault as shown in FIG. 3 (s4).
[0010]
(Equation 1)

[0011]
Next, using the inertia constant M of the system collected and held in s3 by the second information collecting means, and the values calculated in the system capacity _PL0 and s4, the value after the generator is dropped due to the occurrence of a system accident is used. The output operation value _{PG0 '} is calculated according to the following equation (3). The output _PG0 before the generator accident is the difference between the system capacity P _L0 and the loss only, and may be calculated from the system capacity P _{L0 or the} same value may be used for convenience (s5).
[0012]
(Equation 2)

[0013]
Next, a required load control amount _PLC in the entire system is calculated according to the following equation (4) (s6).
[0014]
[Equation 3]

[0015]
Next, the load control amount _PLCi required for the control terminals 3a, 3b is calculated according to the following equation (5) based on the sharing ratio K _i of the control terminals 3a, 3b (s7).
[0016]
(Equation 4)

[0017]
Next, the loads 4a to 4f to be limited or cut off are selected according to the load control amounts _PLCi in the control terminals 3a and 3b, and the circuit breakers 8a to 8f to limit and cut off the selected loads 4a to 4f. A command signal for load limitation is output via the output cable 9 (s8).
The above operations (s1 to s8) are performed by the control terminals 3a and 3b, and the breakers 8a to 8f that receive the command signals from the control terminals 3a and 3b limit the loads 4a to 4f according to the commands. Perform cutoff.
[0018]
In this embodiment, each control terminal 3a, 3b is provided for each bus 1a, 1b, and each control terminal 3a, 3b collects measurement information related to the bus 1a, 1b by the first information collecting means, The frequency F of the system is measured to monitor the frequency F, and system reference information such as the system inertia constant M and the system capacity _{PL0 is} transmitted from the central controller 10 at predetermined time intervals by the second information collecting means. The frequency is stabilized by collecting and calculating the load control amounts of the control terminals 3a and 3b and outputting the load limiting command signals to the circuit breakers 8a to 8f.
Here, the inertia constant M of lines by the second information collection means for receiving from the central controller 10, lineage reference information such as sharing ratio K _i of the system capacity P _L0 and load shedding is accompanied by frequency reduction, as described above It does not change rapidly due to a system accident, but hardly fluctuates, or fluctuates continuously and gradually. For this reason, in the event of an accident, it is necessary to control the load limit in, for example, about 200 msec. However, the reception interval from the central control device 10 by the second information collecting means in each of the control terminals 3a and 3b is 1 every 10 minutes. A long time interval of about two times is sufficient, and an expensive high-speed transmission line is not required.
[0019]
In addition, information that largely changes due to a system accident is collected by the first information collecting means as measurement information relating to the buses 1a and 1b, and the control terminals 3a and 3b are provided for each bus. Thus, information can be collected at high speed through the cable 7. Further, even when the control terminals 3a and 3b calculate the load control amounts and transmit the load limiting command signals to the circuit breakers 8a to 8f, the short output cable 9 can transmit the command signals at high speed.
In this manner, high-speed facilities on the transmission line can be reduced, and cost can be reduced.
[0020]
Embodiment 2 FIG.
In the first embodiment, the output calculation value _{PG0 ′} after the generator is dropped in s5 is calculated by the above equation (3), but may be calculated according to the following equation (6).
[0021]
(Equation 5)

[0022]
In this way, the static voltage characteristic coefficient α of the loads 4a to 4f is set to a predetermined value, and the bus voltage collected in s1 by the first information collecting means is used to calculate the above equation (3). By multiplying by a correction value (V _L / V _L0 ) ^α that takes into account the voltage fluctuations of the buses 1 a and 1 b due to a system fault, it is possible to correct the calculation error due to the bus voltage fluctuations, and to calculate the output after the generator has fallen out. In addition, the calculation accuracy of the required load control amount is improved, and highly reliable frequency stabilization control can be performed.
[0023]
Embodiment 3 FIG.
In the first embodiment, each of the control terminals 3a and 3b receives the inertia constant M and the system capacity P _L0 as system reference information at predetermined time intervals from the central control device 10 at s3. The information may be used to estimate and calculate the inertia constant M and the system capacity P _L0 until the next reception. This estimation calculation will be described below.
Inertia constant M lineages, lineage capacity _{P L0,} each control terminal 3a, respectively, a substantially proportional relationship with the load _{P Li} of the control target of 3b. Therefore, the control terminal 3a by the first information collection means obtains the load _{P Li} of 3b, the following equation inertia constant M, the system capacity _{P L0} in response to changes in the load _{P Li} (7) , According to equation (8). Incidentally, when t ₀ as a reference is usually refers to reception time of the latest it may be that a previous reception time.
[0024]
(Equation 6)

[0025]
For example, if the time interval for receiving the system inertia constant M and the system capacity P _L0 is, for example, 10 minutes, such an estimation calculation is automatically performed during, for example, 5 minutes after reception, and the calculated value is calculated. May be held, or may be calculated when a system fault is recognized in s2, and may be used to calculate the output calculation value _{PG0 '} after the generator is dropped off in s5.
Thus, even if the reception interval by the second information collecting means is large, the reliability of the system reference information is increased by estimating and calculating the information during the interval, and the output calculation value and the necessary load control amount after the generator is dropped Is improved, and highly reliable frequency stabilization control can be performed. Further, even when the reception from the central control device 10 by the second information collection means is interrupted due to some failure, the system reference information estimated and calculated using the already received information can be obtained. Can be performed continuously.
[0026]
In the calculation at s5, the calculation error due to the bus voltage fluctuation may be corrected by applying the second embodiment.
Further, the method of estimating the system inertia constant M and the system capacity P _L0 is not limited to the above-described method. For example, the fluctuation is estimated from the received information of the previous time and the previous two times, and the latest information is calculated by, for example, proportional calculation. May be estimated.
[0027]
【The invention's effect】
As described above, the frequency stabilizing device according to the present invention arranges, for each bus, a control terminal that performs load limiting control connected to a plurality of buses in the power system. A second information collecting unit, a unit for calculating a load control amount using the collected information, and a unit for limiting a load on a load connected to the bus in accordance with the load control amount are provided. In addition, each control terminal collects measurement information related to the bus with the first information collecting means, monitors the frequency of the power system, and uses the first information collecting means with the second information collecting means. System reference information that has less fluctuation due to a system accident than the collected information is acquired from a central control device that monitors and controls the entire power system to be controlled. This eliminates the need for a high-speed transmission line connecting the central control unit and each control terminal, reduces expensive high-speed transmission equipment, reduces the cost of the frequency stabilization system, and reduces the cost of frequency stabilization control. I can do it.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a frequency stabilizer according to Embodiment 1 of the present invention.
FIG. 2 is a flowchart showing an operation of each control terminal in the frequency stabilization device according to Embodiment 1 of the present invention.
FIG. 3 is an image diagram of a calculated frequency deviation of the frequency stabilization device according to the first embodiment of the present invention.
[Explanation of symbols]
1a, 1b bus, 3a, 3b control terminal, 4a-4f load,
10 Central control unit.

Claims (4)

A central control unit that monitors and controls the entire power system to be controlled, and a control terminal that performs load limiting control connected to a plurality of buses in the power system, and the power generation amount due to a system accident in the power system When there is a shortage, in a frequency stabilizing apparatus that controls the frequency of the system by performing load limiting, the control terminals are arranged for each of the buses, and the control terminals collect measurement information on the buses. First information collecting means for monitoring the frequency of the power system, and acquiring from the central control device, system reference information having less fluctuation due to the system accident than the information collected by the first information collecting means. A second information collecting means, a means for calculating a load control amount using the information collected by the first and second information collecting means when the frequency drops, and a means connected to the bus in accordance with the load control amount. negative Frequency stabilization apparatus comprising the means for performing load shedding for. Each of the control terminals acquires the inertia constant and the system capacity of the system from the central control device as the system reference information at predetermined time intervals by the second information collecting means. 2. The frequency stabilizing device according to claim 1, wherein the load control amount is calculated using the system reference information. 3. The frequency stabilizing apparatus according to claim 2, wherein each of the control terminals calculates the load control amount by correcting a calculation error due to a voltage change of the bus. Each of the control terminals may obtain the latest system reference information used in calculating the load control amount by estimating and calculating the system reference information obtained from the central control device up to the previous time. 4. The frequency stabilizing device according to 2 or 3.

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